The invention relates to a modularly expandable semiconductor component having at least one carrier layer, at least one intermediate layer, at least one coverlayer and at least one semiconductor chip placed on the carrier layer. The invention also relates to a method for producing a semiconductor component.
Surface-mounted electronic components, also referred to as SMD components, are typically embedded in a housing which is made of a plastic molding compound, with electrical terminals being led out therefrom. There are a number of different housing construction types, which vary in size and which include a varying number of terminals. A semiconductor chip is first connected therein to a carrier layer. The connecting of the semiconductor chip to the carrier layer is usually accomplished by adhesion, soldering, or alloying. Following the securing of the semiconductor chip, its individual terminal points are connected to terminals of the carrier frame, for instance by using bonding wires. Next, the semiconductor chip and the terminals of the terminal frame are coated in such a way that the semiconductor chip is fully encapsulated and the terminals protrude from the housing.
It is necessary to construct the semiconductor component with optimally small dimensions. Given an optimally small volume, an optimally high storage density, that is to say performance of the semiconductor component, should be realized. If a reduction of housing space consumption is desired, given peripheral external pinning, that can only be done by refining a terminal grid significantly. However, with such a miniaturization of external pinning, one would move closer and closer to the limits of processing capability both in production and in soldering onto the assembly carrier. That necessitates completely new technologies of construction, such as the multichip module (MCM).
In a multichip module, a plurality of semiconductor chips are installed on a substrate adjacent one another in one plane and connected thereto. That permits the realization of internal chip-to-chip connections. Besides plastic leadframe packages, in which the semiconductor chips are installed on a substrate layer and which are coated by a surrounding plastic injection compound following electrical contacting, there are also ceramic packages in existence which have a cavity into which the semiconductor chips are inserted. Three principles of construction can be distinguished:
In a first embodiment, a multilayer wiring system (substrate) is integrated into a housing. That principle is applied primarily in plastic leadframe packages. In a second type of production, the housing already includes a wiring carrier system (cofired ceramic and laminate packages). In a third form, the simplest, the housing includes a construction without a wiring carrier system. It is thus possible to produce a direct interconnection through a wire connection with simple multichip modules having two or maximally three semiconductor chips.
Besides the complicated production of the substrate, as it is known, the primary disadvantage of the multichip modules is that they are unsuitable for economical mass production.
It is accordingly an object of the invention to provide a modularly expandable semiconductor component and a method for producing a semiconductor component, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type, in which a high packing density is achieved given a low volume consumption and in which a high reliability is guaranteed, while simultaneously keeping production costs low.
With the foregoing and other objects in view there is provided, in accordance with the invention, a modularly expandable semiconductor component, comprising at least one carrier layer, at least one intermediate layer and at least one coverlayer respectively disposed above one another; external contacts; a conductor configuration disposed on the at least one carrier layer and leading to the external contacts; and at least one semiconductor chip inserted in the at least one intermediate layer and having contact pads connected to the conductor configuration; the at least one carrier layer and the at least one intermediate layer formed of an at least partly oxidized-through aluminum foil material having a metallic core.
The basic concept of the invention resides in accommodating a plurality of semiconductor chips in one semiconductor component, but with the semiconductor chips being disposed not merely in one plane but rather wherein they may also be installed over one another in several planes. The semiconductor component thus is respectively formed of at least one carrier layer, one intermediate layer, one coverlayer, at least one semiconductor chip with contact pads on a top side, external contacts and an interconnect configuration. The interconnects produce the electrical connection between the contact pads of the semiconductor chip and the external contacts.
In accordance with another feature of the invention, the intermediate layer has at least one opening. This at least one opening serves for accepting the at least one respective semiconductor chip. The printed conductor configuration is located on the carrier layer. The intermediate layer, the carrier layer and the coverlayer are connected to one another in such a way that they lie one over the other. The component is further constructed in such a way that the printed conductors of the carrier layer terminate on one hand in a region near the semiconductor chip, and on the other hand in an edge region of the semiconductor component.
An advantage of this type of component construction is that the semiconductor component can be manufactured with known production methods and materials. The carrier layer is formed of an aluminum foil that has been completely or partly oxidized through, and on the top side of which conductors are etched or printed. The production methods of printed circuit boards (PCB) can be used for this purpose. Like the carrier layer, the intermediate layer also is formed of aluminum foil that has been completely or partly oxidized through. Aluminum foil that has been oxidized through at least partly has the advantage of ensuring that the coefficients of thermal expansion are better suited to the values of semiconductor chips and plastic molding compound. Furthermore, aluminum foil undertakes an insulation of the individual layers from one another. If a metallic aluminum core remains in aluminum foil that has been partly oxidized through, then this core assumes an electrical shielding of the respective intermediate layers or carrier layers that are located over one another. An inclusion of moisture is also prevented. A further advantage is a more cost-effective production of aluminum foil as compared to the use of FR4, a common substrate. Openings are stamped or embossed into the intermediate layer and it is also possible to use any other known method of production. This production step is also known.
In accordance with a further feature of the invention, the coverlayer is formed of a material which dissipates heat well and which is well suited to the values of the carrier layer and the intermediate layer regarding coefficients of thermal expansion.
In accordance with an added feature of the invention, the semiconductor component is composed of what are known as submodules. A submodule is formed of a carrier layer, onto which an intermediate layer has been laminated on both sides, as well as one or two respective coverlayers. The coverlayer or coverlayers are applied on the other side of the intermediate layers and form a termination of the semiconductor component. This means that one side of an intermediate layer has the coverlayer and the other side of an intermediate layer has the carrier layer. Since both the coverlayer and the carrier layer have a planar surface, a plurality of these submodules in one-sided or double-sided embodiments can be combined into one semiconductor component. The one-sided submodule is formed of a carrier layer and an intermediate layer applied on one side and covered in turn by a coverlayer. A double-sided submodule is constructed in such a way that the carrier layer is provided with an intermediate layer on both sides, with the still-exposed side of the two intermediate layers being covered by a respective coverlayer.
Since each intermediate layer has an opening in which at least one semiconductor chip is respectively inserted, joining several submodules above one another achieves a stack of semiconductor chips in the third dimension. A high packing density of the semiconductor component is thereby achieved given a low volume requirement.
In accordance with an additional feature of the invention, the ends of the printed conductors, which are situated in the vicinity of the at least one semiconductor chip, are positioned on the carrier layer in such a way that the ends of the printed conductors become situated inside the opening or openings located in the intermediate layer.
In accordance with yet another feature of the invention, in a double-sided submodule, the printed conductors are placed on both sides of the carrier layer. However, it is also conceivable for the printed conductor configuration to be placed on both sides of the carrier layer in a one-sided submodule. This imparts the advantage of permitting the guiding of the printed conductors to be accomplished with greater flexibility.
A further advantage of the semiconductor component according to the invention is that the carrier layer is constructed similarly to a PCB. This makes it possible to integrate housed as well as unhoused semiconductor chips in the semiconductor component. The semiconductor chips can be applied to the carrier layer through the use of a flip-chip process and can also be glued or laminated onto the carrier layer with their unstructured back sides and electrically connected to the printed conductors by a wire-bonding process or a spider strip. The semiconductor chips that sit in the openings can be surrounded by a plastic molding compound subsequent to the electrical contacting process or, if the reliability thereof is guaranteed, they can also sit in the opening without the molding compound.
In accordance with yet a further feature of the invention, there is provided at least one passive component integrated on the carrier layer. The passive components can be electrical resistors, capacitors, or the like, for example.
In accordance with yet an added feature of the invention, the coverlayer advantageously extends beyond the intermediate layer and the carrier layer on a side at which there are no external contacts disposed. In this case, the coverlayer is constructed as a heat distributor. The heat distributor that projects beyond the intermediate layer and the carrier layer can be optimized to the heat loss of the semiconductor component that must be dissipated. The greatest thermal power loss can be dissipated when the coverlayer extends beyond the intermediate layer and the carrier layer on all sides at which external contacts are not disposed.
In accordance with yet an additional feature of the invention, the carrier layer extends beyond the intermediate layer and the coverlayer on the side at which the external contacts of the semiconductor component are disposed. The external contacts can thus be constructed as plug connections. When the printed conductors are led to the end of the carrier layer, subsequent to the application of metallizations at the ends of the printed conductors, a plug connection can be produced which is electrically contacted to a subassembly, module or board carrier. However, it is by all means also conceivable to construct the external contacts as pins.
In accordance with again another feature of.the invention, when the metallization contacts of the plug connection are attached to the carrier layer on both sides in an opposing manner, it is conceivable that the two metallizations conduct the same electrical signal or that each of the two metallizations conducts a separate electrical signal. This is advantageous above all when the printed conductors are attached to the carrier layer on both sides.
In accordance with again a further feature of the invention, in order to ensure a correct attachment of the semiconductor component on a subassembly carrier, the carrier layer includes a mechanical coding, for instance in the form of a recess or a polygonal cutout on a corner side. The mechanical coding can assume any conceivable form, as long as it is guaranteed that an incorrect contacting on the subassembly carrier is prevented.
In accordance with again an added feature of the invention, in order to keep the number of external contacts optimally low, and thus to simplify the installation and the course of the printed conductor configuration, it is advantageous that all semiconductor chips that are located in the semiconductor component are supplied through a common printed conductor. This means that, given n semiconductor chips, (nxe2x88x921)*2 external contacts can be spared. Printed conductors within the semiconductor component provide for the electrical connection of the contact pads of the semiconductor chip, which serve, along with the respective external contacts, for supply.
Semiconductor chips of different types can be contained in the semiconductor component according to the invention. For example, these can be memory chips and/or processors. The semiconductor chips can be connected to one another through printed conductors as long as the semiconductor chips lie in one plane.
In accordance with again an additional feature of the invention, with the aid of through-platings which are located in the carrier layer or the intermediate layers, it is possible to electrically interconnect semiconductor chips that are located in different planes.
In accordance with still another feature of the invention, if semiconductor chips that are located in different submodules are to be connected, then the coverlayer and the carrier layer include what are known as contact interfaces. The contact interfaces are attached in such a way that they overlay each other precisely when the carrier layer of one submodule is connected to the coverlayer of another submodule. If the connection of the two submodules is carried out by using an anisotropic glue or adhesive, the electrical connection of the contact interfaces of the two intermediate layers is simultaneously ensured. It is also possible to use soldering pastes or solder balls for the electrical connection, whereby the connection of two submodules can then be produced through the use of adhesion or lamination. An anisotropic conductive glue or adhesive has the advantageous characteristic that it is conductive in direction y, for example, while at the same time being electrically insulating in direction x. At the same time, it undertakes the secure mechanical connection between a carrier layer and a coverlayer. The contact interfaces are electrically connected to a through-plating, which in turn is electrically conductively connected to a printed conductor on a carrier layer.
The advantage of the semiconductor component according to the invention resides in the ability to accommodate in one submodule groups which belong together functionally.
Semiconductor chips of different types can be combined in one submodule, for instance memory chips with processors. Furthermore, it is possible to integrate passive components in one submodule. Since the two sides of a submodule, that is a cover layer and a carrier layer in a one-sided submodule and two coverlayers in a double-sided submodule, are planar, a plurality of submodules can be placed over one another, connected, and combined into a very compact semiconductor component. Due to the compact configuration of the respective individual semiconductor chips in one or more submodules, or of the passive components, a very good signal performance is guaranteed, above all at higher frequencies, based on the short signal lengths. Furthermore, it is possible to electrically connect semiconductor chips in one submodule to one another, as well as to connect semiconductor chips in different submodules to one another through contact interfaces. In a double-sided submodule, very short signal paths can be created between two semiconductor chips when they are attached to the carrier layer in a mirrored manner, and when the electrical contacts are connected to one another through the use of through-platings through the carrier layer. Furthermore, a good heat dissipation is guaranteed by the integrated coverlayers, which are applied on every intermediate layer. By virtue of the placement of a plurality of submodules over one another, a smaller deformation of the completely equipped and sealed semiconductor component is guaranteed. A cost-effective production of the semiconductor component is possible, since known production technologies and manufacturing tools can be used. A flexible combination of different functional subassemblies is possible on the basis of the modular construction of the submodules.
With the objects of the invention in view, there is also provided a method for producing a semiconductor component formed of one submodule. In a first step, a carrier layer is equipped with a printed conductor configuration and, if so desired, with passive components. Next, the carrier layer is connected to an intermediate layer, which has at least one opening. The connection is advantageously accomplished by lamination. At least one semiconductor chip is inserted into the opening of the intermediate layer and this chip is connected to the carrier layer. The semiconductor chip can be placed on with its structured side on the carrier layer (face down) or with its rear side thereon. Next, the semiconductor chip is electrically contacted to the printed conductors. The ends of the printed conductors are installed on the carrier layer in such a way that they project into the opening of the intermediate layer. Following the electrical contacting process, the opening can be filled with a plastic molding compound, but need not be. In a last step, a coverlayer is applied to the intermediate layer, thereby covering the at least one opening of the intermediate layer. The coverlayer is connected to the intermediate layer securely, for instance by lamination. In a final step, metallizations are applied to the ends of the printed conductors, which are located on the carrier layer that projects beyond the coverlayer and the intermediate layer on the side at which the external contacts are provided.
If a double-sided submodule is to be produced, an intermediate layer having at least one opening is applied on the second side of the carrier layer, and at least one semiconductor chip is inserted in the opening and electrically connected to the printed conductors in turn. Next, a coverlayer is applied to the second intermediate layer. The coverlayer advantageously projects beyond the carrier layer and the two intermediate layers on all sides at which external contacts of the semiconductor component are not accommodated. The metallizations on the carrier layer, which form the external contacts, can be attached to the carrier layer on one or both sides.
With the objects of the invention in view, there is additionally provided a second method of production which differs from the method just described in that the semiconductor chips are first placed on the carrier layer having the printed conductors and the passive components, and are securely connected. Next, the contact pads of the semiconductor chips are connected to the printed conductors of the intermediate layers, for instance with the aid of bonding wires. The semiconductor chips can be placed onto the carrier layer on one or both sides. Only then is an intermediate layer having openings at the locations of the semiconductor chips on the carrier layer applied to the carrier layer on one or both sides and connected thereto, for instance by lamination. The semiconductor chips situated in the openings can be sealed with molding compound. The subsequent production steps run in accordance with the first production method.
In accordance with a concomitant mode of the invention, if a plurality of submodules have been produced in accordance with one of the two described production methods, then a plurality of submodules can be connected into one semiconductor component. In this case, the base is a double-sided submodule on which one or more one-sided submodules are respectively installed. This means that the semiconductor component is always enclosed by a coverlayer on the two opposite sides. Two submodules are always joined in such a way that a coverlayer is connected to an intermediate layer.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a modularly expandable semiconductor component and a method for producing a semiconductor component, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.